F33 cutless bearings

[Rodent]

Anyone have experience of the propellor shaft and cutless bearings on the F33?

My boat was built in 1982 in the US. The survey, when I bought her last July, pointed out play in the cutless bearing, so last week I removed the prop, shaft and cutless bearing. On removing the prop the cutless bearing (which was 4" long) fell out of the stern tube with no prompting, the metal outer being well worn down. On removing the shaft I found a second cutless bearing (only 3" long this time) some 190mm/7.5" in from the aft end of the tube. No grub screws holding it in place, and it came out without too much trouble - the metal was much less worn than the other one, but the rubber inner was well worn down. Where it had been the shaft was well worn down from its 1" diameter, so the bearing had been in that position for some time. Does anyone know whether the F33 was fitted with a second cutless bearing, and if so where should it be located on the shaft. Is it a bearing which was originally fitted at the forward end of the stern tube, and which has worked its way aft, down the incline of the tube, or do you think it might be an original aft end bearing that someone has pushed up the stern tube rather than removing the shaft and bearing when a new bearing was being installed?

Roy Denton.

[Michel]

Roy,

I used to have a UK built F33/35, so there may have been differences. I once replaced the cutlass bearing.
As far as I remember, my cutlass bearing was brass on the outside, 6" long, had grub screws and lubrication holes to be lined up with the scoops on the keel sides.

Some observations based on your findings:
- outside of cutlass bearings is usually brass or plastic, so your bearings must have been there for a long time. Are they steel?
- two cutlass bearings after the other is something I've never heard of. I'd consider it an uncommon PO modification. The PO probably found the stern tube quite long and empty and decided a second inner cutlass bearing wouldn't hurt. Which I fear is not true.
- cutlass bearings need an ample supply of water to cool and lubricate, water enters either along the shaft, or better, with small scoops on the sides of the keel.
- based on the difference in wear between your inner and outer cutlass bearing, either your inner cutlass bearing was too small in diameter and squeezed the shaft, it had too little cooling and got hot or your engine drive train is out of line.

To prevent centripetal forces of the shaft and prop flying around in circles, the idea is that the cutlass bearing is set as far aft as possible, as close to the prop as you can get it. Perhaps you have unnecessary shaft length, putting greater loads on the inside of the cutlass bearing and creating vibration. If your shaft is out anyway, shortening is a small task.

I would replace the two bearings with one outside bearing, 6"long, of the proper inner and outer diameter and a non-corroding outside. If the cutlass bearing apparently fits loose in the stern tube, first check engine and shaft alignment. Fill the void between stern tube and bearing with epoxy while preserving your shaft alignment. Also make sure the cutlass bearing is not glued stuck inside the stern tube; use a good release agent and/or a mock-up bearing(e.g. cardboard tube) of the right size while the epoxy is curing. Place the bearing in the tube, as far aft as possible. My bearing stuck out of the tube a 1/2". Open up the scoop holes and grub screw holes. Then place the bearing with silicone grease both inside and out, align the scoop holes and grub screw holes and you should be done.

[AlanK]

I have a 1982 US built Freedom 33 Hull #51.
I changed the cutlass bearing in 2009. The old one was sliding on the shaft so it had moved forward. It was difficult to get at and remove. It was 3".
I'm guessing that in your case the same thing had happened and the PO or mechanic just put another one on.
I put in new set screws to hold the new cutlass but find that with enough pressure that just distorts the bearing put pressure on the shaft so it doesn't spin freely until the rubber wears down.
My solution has been to adjust the set screws to the maximum pressure that doesn't interfere with free spinning of the shaft. And let an 1/8inch of the bearing extend out of the boat so the metal is exposed. I used 5200 bedding compound on the metal so the bearing can not slide in and small amount of it sticking to the hull is easy to remove but effective at least so far.

[Rodent]

Hi Michel and Alan - thanks for the responses.

There is no extra shaft length that can be cut off, and I need to decide if the wear is so great I need a new shaft. The bearing outers are both brass. The rearmost one is so worn the inner rubber is exposed on the outer face in places, and I think the stern tube has been worn by the bearing rotating within it. To remove the forward bearing I used threaded rod and some 30mm diameter washers as a puller. 32mm washers would go in the end of the stern tube some way, but not very far, so I used 30mm. Now I think the outer diameter of the bearings new would be 1.25" (which is 31.75mm) and the fact that the 32mm washers will go in some way indicates wear on the tube. I then need to decide if this wear can be accommodated in some way, or if the whole or part of the stern tube needs replacing. Any ideas welcome.

Roy.

[Michel]

Perhaps a bearing with a greater OD fits better into your stern tube. Or use epoxy putty to fill the void around the bearing (use release agent on the outside of the bearing!) As long as your shaft is smooth at the watertight seal on the inside end, a bit of wear wouldn't hurt, i think, although it may create some extra wear on the rubber of the cutlass bearing.

[Rodent]

Just received a new cutlass bearing - 1" inner, 1.25" outer diameter. Now I will order a new shaft and build up the internal face of the stern tube, placing polyester resin and chopped strand mat, then sanding back until the bearing is a close fit.

Thanks for your help.

Roy Denton.

[whimsy]

I've also got a cutless bearing issue on my F33. So far I've got everything apart, except for my "bonus" cutless bearing.

My stern bearing is worn, and my shaft is a little scored at that location. There was probably sand thrown in there when I tried to back off of a grounding a while ago, but I also have vibration issues. I have just modified one engine bet so that the engine mount base is at the angle it should be at for the first time; I'll see if the engine behaves better at low speeds when I'm back in the water...after all this work!

My stern tube is a fiberglass tube with no evidence of any set screws or ports to encourage moving water in there. There is a 4" bearing at the end of the tube. There also appears to be another old bearing about a foot farther in the tube. It has not been replaced since I've owned the boat. This one won't be easy to get out, as it is too far in to cut, and the yard used some epoxy to tighten up the fit on the tube at the stern, molded around the bearing. That likely left a lip at the forward end of the aft bearing which may stop the other one from coming out.

I also have a drip-less PSS shaft seal. To make sure there is water there, they come with a hose fitting, and for slow boats (<12kt) you can just have it open to air above the waterline, which is how it was installed. Their instructions include using the other method (pressurized water, usually tapped off of the raw water cooling before the mixing elbow) for faster boats. This sentence appeared in the more recent (since mine was installed) instructions from PYI: "However, displacement boats with a bearing in the shaft log must plumb water to the seal." I believe they are talking about me in that sentence.

One other vibration issue is the maximum unsupported shaft length. I found an equation here: http://www.pacificmarine.net/engineerin ... pacing.htm and working it out found that my answer was 53 or 58 inches at 3600RPM (Depending on the reduction in my transmission; All the specs I found said 2.21 or 2.62 FWD / 3.06 REV) My shaft is about 59" long, and about 46" from the end of the coupling/key to the front of the stern bearing.

Googling I found somebody else who had troubles with this when they went from conventional packing (i.e. a shaft support at the fwd end of the shaft log) to drip-less (i.e. unsupported) and fixed this by putting an extra cutless bearing in shaft log just past the shaft seal.

OK, enough background. Now my questions/issues:

• Plumbing my cooling water to the PSS shaft seal seems easy enough and a good idea for cooling/lubrication of both the PSS and the cutless bearing. Right?
• How much scoring on the shaft at the cutless bearing is "too much"? i.e. should I replace the shaft?
• Should I put a second cutless bearing at the fwd end of the shaft log by the PSS?
• If I have a somewhat worn cutless bearing in the middle of my shaft log, can I just leave it there without causing problems?

[GeoffSchultz]

I have a PSS on my 40/40 and there's no reason to plumb water to the shaft. There's plenty of water available to keep it lubricated/cool. I would suggest that you put an anti-siphon on the top of the vent line and take another piece of hose and run it to the bilge. I've had situations where air got into the shaft log and bubbled out of the vent line bringing a lot of water with it...which splashed into galley drawers which are located in front of where the vent hose is located. Needless to say the admiral wasn't happy.

I can't answer your question about the scoring. Your yard and/or a shaft dealer should be able to. What you don't want to do is to replace the cutlass bearing and have it wear away right away due to a scored surface.

I didn't read the link to the equations, but just remember that you need to divide the engine RPM by the transmission reduction to give you prop RPM. I do know that Freedom seems to have used the absolute minimum shaft that they could get away with. For example, I have a 1 1/8" shaft and it would be much better to have had a 1 1/4".

-- Geoff

[whimsy]

One reason I'm thinking of plumbing water to the PSS is that my cutless bearing has no vent holes for water flow, and no set screws to hold it in place. I can use a little epoxy to hold the new one in place (Yes, I will wax the bearing before I glue it in!)

I'm also thinking of drilling/tapping for set screws, but my stern tube is fiberglass. Will that work?

[GeoffSchultz]

I'm quite confused. I have 1 cutlass bearing and it's on the strut near the prop. Do you have another? I was confused about by the writeup as to what is actually there.

-- Geoff